Method for graphically representing an image from an image sensor superimposed on a synthetic second image of the outside landscape

Abstract

The general field of the invention is that of the methods for graphically representing a first image from an image sensor of the outside landscape superimposed on a second image representing a synthetic image of the same outside landscape, the two images being displayed on a display screen of an onboard display system for aircraft. The first image comprises three rectangular zones of increasing transparency, each zone having a width equal to that of the first image and a determined height, the sum of the three heights being equal to the height of the first image, the first zone situated at the bottom of the image having a first constant level of transparency, the third zone situated at the top of the image having a second constant level of transparency greater than the first level of transparency, the second zone situated between the first zone and the third zone having a level of transparency that is continuously variable between the first level and the second level.

What is claimed is: 
     
       1. A method for graphically representing a first image from an image sensor of the outside landscape superimposed on a second image representing a synthetic image of the same outside landscape, the method comprising:
 displaying the first image and the second image on a display screen of an onboard display system for aircraft, wherein the first image comprises three rectangular zones of increasing transparency, each zone having a width equal to that of the first image and a determined height, the sum of the three heights being equal to the height of the first image, the first zone situated at the bottom of the image having a first constant level of transparency, the third zone situated at the top of the image having a second constant level of transparency greater than the first level of transparency, the second zone situated between the first zone and the third zone having a level of transparency that is continuously variable between the first level and the second level, the heights of the three zones being adjusted automatically by the onboard avionics system as a function of the altitude or the radio altitude of the aircraft. 
 
     
     
       2. The method of  claim 1  wherein the height of the first zone represents 30% of the height of the image, the height of the second zone represents 50% of the height of the image and the height of the third zone represents 20% of the height of the image. 
     
     
       3. The method of  claim 1  wherein the first level of transparency is nil or close to zero and in that the second level of transparency is greater than 80% and strictly less than 100%. 
     
     
       4. The method of  claim 1  wherein the law of variation of the level of transparency of the second zone is linear. 
     
     
       5. The method of  claim 1  wherein the heights of the three zones can be adjusted automatically by the onboard avionics system as a function of the flight phase of the aircraft. 
     
     
       6. The method according to  claim 1  wherein the heights of the three zones can be adjusted automatically by the onboard avionics system as a function of a distance to the terrain in the field of the sensor computed from the terrain database. 
     
     
       7. The method of  claim 1  wherein the heights of the three zones can be adjusted automatically by the onboard avionics system as a function of the limit of visibility of the image sensor. 
     
     
       8. The method of  claim 1  wherein the first level of transparency and/or the second level of transparency vary as a function of the altitude of the aircraft when the aircraft is ascending, so that the first image is increasingly transparent as a function of the altitude, the changes of levels of transparency beginning at a first low altitude threshold and ending at a second high altitude threshold, the first image being totally transparent at the second high altitude threshold. 
     
     
       9. The method of  claim 1  wherein the first level of transparency and the second level of transparency vary as a function of the altitude of the aircraft when the aircraft is descending, so that the first image is increasingly opaque as a function of the altitude, the changes of levels of transparency beginning at a third high altitude threshold and ending at a fourth low altitude threshold, the first image being totally transparent at the third high altitude threshold. 
     
     
       10. The method of  claim 9  wherein the first low altitude threshold and the fourth low altitude threshold have different values and/or the second high altitude threshold and the third high altitude threshold have different values.